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v.out.ascii - Convert a GRASS binary vector map to a GRASS ASCII vector map




v.out.ascii help
v.out.ascii [-o] input=name [output=string] [format=string] [dp=integer]


Create old (version 4) ASCII file


Name of input vector map
Path to resulting ASCII file or ASCII vector name if '-o' is defined
Output format
Options: point,standard
Default: point
Number of significant digits (floating point only)


v.out.ascii converts a GRASS vector map in binary format to a GRASS vector map in ASCII format. Using flag -o v.out.ascii output will be in old (version 4) ASCII format.

If the output parameter is not given then the coordinates of any point data within the vector file is sent to stdout.


The GRASS program performs the function of v.out.ascii in reverse; i.e., it converts vector files in ASCII format to their binary format. These two companion programs are useful both for importing and exporting vector files between GRASS and other software, and for transferring data between machines.

If the format parameter is set to standard, A GRASS ASCII vector file will be exported, which may contain a mix of primitives including points, lines, boundaries, centroids, areas, faces, and kernels. The beginning of the output ascii file will contain a header listing any metadata for the input vector, if such metadata exists. An example of the standard format is given below.

The primitive codes are as follows:

The coordinates are listed following the initial line containing the primitive code, the total number of vectors in the series, and the number of categories (1 for a single layer, higher for multiple layers). Below that 1 or several lines follow to indicate the layer number and the category number (ID).

The order of coordinates for new (standard) version of ASCII file is

X Y [Z]

the order of coordinates for old version of ASCII file is


If old version is requested, the output files from v.out.ascii will be placed in the $LOCATION/$MAPSET/dig_ascii/ and $LOCATION/$MAPSET/dig_att directory.

Only features with a category number will be exported. Use v.category to add them if needed.

v.out.ascii does not copy the dig_cats file associated with the binary vector input map to the new output file name. The user must copy the dig_cats file to the new output name if this is desired (e.g., using the UNIX cp command).

It is possible to output the coordinates of vertices in a non-points vector feature by first converting the vector feature to a points map with and then exporting with v.out.ascii in points mode.


Example 1a) - standard mode - using the 'quads' vector from Spearfish dataset:

v.out.ascii input=quads format=standard

ORGANIZATION: US Army Const. Eng. Rsch. Lab
DIGIT DATE:   May 1987
DIGIT NAME:   grass
MAP NAME:     Quads
MAP DATE:     May 1987
MAP SCALE:    24000
ZONE:         13
MAP THRESH:   18.288000
B  4
 599587.1820962 4914067.53414294
 589639.15126831 4913922.5687301
 589440.96838162 4927803.62500018
 599375.87959179 4927959.83330436
B  2
 599375.87959179 4927959.83330436
 599587.1820962 4914067.53414294
B  4
 599587.1820962 4914067.53414294
 609541.5508239 4914236.0597482
 609316.10665227 4928116.8490555
 599375.87959179 4927959.83330436
C  1 1
 594125.63    4921115.58
 1     1
C  1 1
 604433.84    4921087.1
 1     2

Example 1b) - point mode

v.out.ascii input=quads format=point




Vector ASCII Format Specification


Michael Higgins, U.S. Army Construction Engineering Research Laboratory
James Westervelt, U.S. Army Construction Engineering Research Laboratory
Radim Blazek, ITC-Irst, Trento, Italy

Last changed: $Date: 2006/08/31 14:25:37 $

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